Process for directly converting sugar syrups into crystallized sugar of agreeable taste.



T G. GRIERE.

PROCESS r03 DIRECTLY CONVERTING SUGAR SYRUPS INTO ORYSTALLIZED SUGAR 0F AGREEABLE TASTE.

APPLICATION FILED M11117. 1909.

Patented Mar. 28, 1 911.

2 SHEETS-SHEET 1- m NEw/i 0. GRIERE.

PROCESS FOR DIREOTLY CONVERTING SUGAR SYRUPS INTO GRYSTALLIZED SUGAR 0? AGREEABLE TASTE.

APPLICATION FILED MAR. 1']. 1909.

Patented Mar. 28, 1911.

, 2 SHEETS-SHEET 2.

v srnrns PATENT; Quince,

enemas ear-Ens, or sane-Enemies, GERMANY:

PROCESS FOR DIEECTTJT CONVERTING SUGAR SYBUPS IMO CRSEALI|IZED S'gq'A Ii' AGBEEABLE TASTE. I

Specification otLtters latent. Patented Mar Application filed. na e 17, 1909. ser No, sauces.

My invention relates to a process by which beetroot sugar such as 'is obtained in a rough state in sugar factories may be given an agreeable taste and smell similar to that of cane sugar and also to convert the rawsugar into different varieties of crystallized sugar such as powdered sugar, grain sugar and clayed sugar or cassonade in the, simplest and most economical way.

In carrying out the rocess, I may, for instance, boil down a so ution of sugar which may be more or less pure but is preferably of a high degree of purity, at atmospheric pressure in a comparatively short time to such an extent that its boiling point is raised to from 120130 C. The sugar solution is then run off into a mixing tank of any suitable shape and a determined quantity of crystallized sugar of the fineness desired in the finished product added. As much as 50 to a 100% or even' more of crystallized su ar may be added. to the solution. In a ew minutes crystallization will ensue and-owing to the action on the water contained in the mass, of the heat induced or generated by the crystallization, the mass will start to give ofi' steam, and a of from 70 to 80 C. will be formed. Then the :contents of *the mixing tank are transferred into a secondtank \wherethe mass is still further stirred. From this tank the sugar is fed slowly into a feeding screwof special construction. This :feeding screw has a rapid motion 'anda current of coldair is sent through the mass=as it asses through thescrew. The sugar-issues rom the sorew as a-dry powdery mass-and isithen passed through -a screen. It is to be understood that although thisairis referred to as cold,. 1t only needsto be cooler than the. paste, and

paste of moist sugar.

nary or usual temperature in which the op;

erat ons. are carried on.

If, as in the case described, the syrup is boiled down at atmospheric pressure and it may be somewhat warmer than the ordia;

also if the boiling has been at first carried on in a vacuum, it is absolutely necessary to carefully prevent the boiling solution from coming into contact with the surrounding atmosphere. This is done by continually maintaining a layer of steam over the boiling syrup. In this case, the evaporation L'eceptacle is provided with a' suitable cover and the steam is maintained in the space between the surface of the solution and the said cover, so that no air can have access to the solution. Owing to this precaution the sugar is not decomposed and the product does not show the coloring and the disagreeable odor consequent on such decomposition, but on the contrary a favorable change is produced in the finished product.- Thehi ghq temperature of about 125 C. acting during a'short period of time, and also the su $c-' quent treatment, gives the sugar a character'- :istic smell and taste withoutipchanging its color. .Beetroot sugar may in manner be given an odor and taste similar to that .015

cane sugar.

The complete erystalilization of addition of powdered sugar is .a physical phenomenon which is not dependent on the stirring of the mass, but is brought aboutiby the fall in :the temperature .of the solution I a. a: ready highly voiversaturated solution 011 the consequent on-the additionof the sugar, and

by the dry sugar absorbing a large quantity of the water of the solution. tllhe mass is stirred .only to distrib'ute the materials as equally as .possible'. It is ,not necessary to heat or cool the mass further durin ,the process. The initial 'heat .of the solution is suificient. If the stirring tank should be subjected .to any-strong cooling .influence it should preferably be protected by acasing.

The mass in :the mixing :tank .should not :be

allowed to cool down too'far or to lose I-t00 much water. i

"Thelmass should be .kept in .a pasty state,

since, if it gbecomes too .dry, hard -.lumps of sugar are formed, .which will n0t pass through the screen and which occaslon a large quantity .of waste. .The crystallized sugar is finally dried by a current of cold air blown into the feeding screw aided by the mechanical action of the screw itself.

A process is known according) to which powdered sugar may be obtained y strongly agitating a sugar solution boiled down to 120 C. by means of a rapidl moving stirrer. This process is in accor ance with the known properties of highly concentrated sugar solution heated to a high temperature. In my process I utilize the properties of certain solutions known inchemical science in a new manner. I divide the operation into two well defined phases: first, the production of a paste of sugar crystals; and second, disintegration and drying of that paste to produce crystallized sugar. By this means I am enabled to carry out my process with a high degree of exactitude and to regulate to a certain degree the size of grain of the product obtained. It is of great importance to keep the hot and moist sugar paste in the mixin tank homogeneous and this is greatly facilitated by the possibility of working at a determined temperature in a certain time and with an exactly determined quantity of material. The conversion of the paste into dry powdered sugar is also rendered simpler and more exact according to the present process as it is possible to regulate singly each of. the three agents, namely, the temperature of the sugar paste, the action of the screw, and the air current.

In practice the sugar syrup is boiled down in a vacuum pan such as is used in sugar fac tories. In order to accelerate this operation, a vacuum is maintained in the pan and it is gradually reduced so that the solution never becomes supersaturated to such a degree as to produce granulation. Finally the vacuum valve is closed altogether and the air valve opened. The concentrated solution is then run into a mixing tank preferably of small diameter and the crystallized sugar added in predetermined quantity. As a part of this sugar there may be employed all the waste sugar of the factory, the lumps that remain on the screen, the su ar from the dust chamber, etc. It is posslble to determine to some extent the size of grain of the sugar obtained by the manner in which the addition is made. If the quantity of sugar added is small and the mixture is stirred for a comparatively short time few crystals are formed and these grow to some size. If however a large quantity of sugar is added snizll crystals in great quantity are the resu For mixing the sugarand the syrup I preferably employtwo distinct devices, the one adapted to mix the ingredients and the other'to knead the paste thoroughly. For both purposes I may employ any form of mixlng apparatus known in the manufaceeaaei ture of sugar and other industries. It is however important that the mixmg arms continually scrape along the walls of the tank-as the paste has a tendency to harden and adhere strongly to the walls when it grows cold. I therefore fit the mixing arms with scrapers. I may also carry out both I operations in the same mixing apparatus if desirable.

The air current may act on the paste as a counter current and in this case the air is introduced under pressure at one end of the screw and leaves it by an opening placed 7 close to the opening by which the paste is fed into the screw, or it may be' introduced into the screw from both ends and leave it in the middle.

Instead of adding a certain quantity of sugar or waste to the concentrated syrup, crystallization may also be brought about by evaporation of a certain amount of water from the syrup. In this case the mixing tank must be closed. The syrup is run in anda vacuum produced in the tank. The syrup immediately begins to crystallize. As in the case above described crystallization is accompanied by the generation of steam and this phenomenon may be utilized to determine within certain limits the size of the grain obtained. If at first only a small amount of the water in the syrup is allowed to evaporate and the tank is then opened and crystallization allowed to proceed under atmospheric pressure and stirring, comparatively few crystals, of larger size will be formed. If however sugar of a finer grain is desired, crystallization is brought about as before and then the pressure lowered more and more till crystallization is complete.

In the first case the sliding valve of the vacuum is opened for a few minutes so that only a few centimeters minus pressure is produced in the tank and the valve again closed. It may then be easily seen on opening a small cock on the tank by the steam issuing from it thatover pressure has taken theplace of the vacuum. This is a sign that crystallization is beginning. The grain grows rapidly and the vacuum valve may soon be again opened.

In the second case the sliding valve is opened gradually so that the pressure is gradually lowered. The operation is finished in from 10 to 15 minutes accordingly as the sugar is desired more or less moist. In case a second mixing tank is used evaporation may be so conducted as to obtain a paste of the same degree of viscosity and temperature as when working by addition of waste sugar. The paste is then treated as before described. If the mass is kept a little longer under the influence of the vacuum it begins to disintegrate in the tank and a moist sugar of 60 to 70 C. is obtained. It is perfectly useless-and even detrimental to cool the sugar still further and in any case the sugarmust.

waste. It is not necessary to establish a high vacuum in the tank, an ordinary low pressure from 55 to 60 cm. is quite sufliclent and even preferable. The moist sugar which leaves the mixing tank according to the above described manner of working may be dried by the same form of feeding screw as.

the above mentioned paste.

Both these modifications of my process have this in common that they begin by converting highly concentrated and heated sugar solution into a moist paste of crystallized sugar by depriving it of part of its water either by evaporating part of said water or by addlng a determined quantity of dry sugar and at the same time lowering the temperature of the solution. The moist and heated paste of crystallized sugar is in both cases converted into dry powdered sugar by treating it with a current of air which absorbs the rest of the water and cools the mass still further.

The advantage of the present process over other similar methods of preparing powdered sugar or converting filling masses into dry crystallized sugar is its simplicity, the certainty of attaining the desired result andthe ease with which the different operations may be controlled. The present process also saves labor and fuel.

It is evident that the two modifications described may also be combined to form a third modification. To do this I add a. smaller quantity of sugar to the solution than I would in working'according to the first method and then lower the pressure but not as much as is necessary for carrying out the second method. This manner of working produces the same results as the above mentioned modifications.

The present process is especially designed for treating beetroot sugar but it may of course be also used to convert cane sugar syrups into crystallized sugar. In case of cane sugar syrup being employed it would be useless and even dangerous to boil the syrup down to so high a boiling point. It is preferable to employ syrup of a lower temperature and add more dry sugar or allow the vacuum to act a few minutes longer. It is further evident that the above described results may also be obtained from beetroot sugar syrups of lower temperature than 125 C. and in case it is not desired to modify strongly the smell and taste of the finished product it will not be necessary to boil down the syrup to that extent.

In the accompanying drawing, Figure 1 is a longitudinal section of a mixing tank ada ted for use in carrying out the improved met od, Fig. 2 is a transverse section through fitted with a shaft the tank, Figs. 3 and 4 are a longitudinal section and a transverse section, respectively, of a mixing tank of modified form, and Fig. .5 is a longitudinal section through a feeding screw through which drying air is passed.

The mixin tank (Fig. 1) consists of a barrel shape trough a open at the top and b. The shaft is provided with stirring arms 0 which carry horizontal scrapers d. The shaft is rotated by a worm gear 6. The trough a may be rocked by means of a spur gear f geared by the cog- ,wheel 9 to the shaft h and pulley 2';

. If it is desired to work under reduced pressure in the trough a it should be fitted ,With a cap, pipes connecting it to the air pump and an air valve.

The second mixing tank (Figs. 3 and 4) is similar in construction to the first the only difference being that no arrangement is made for rocking the tank. The scrapers d are inclined against the axis of the shaft and feed the pasty mass toward the discharge opening 1: which may be closed by a door 8.

Instead of these two forms of mixing tanks one single tank may be employed which should then be fitted with mixing and kneading arms. The feedin consists of a closed cylindrlcal trough l in which a shaft m rotates. This shaft carries stirring arms n and alternating with these spiral screw blades 0- which may be full or composed of strips of metal. The current of air is introduced through an opening p near the discharge opening and leaves the screw through the feed openin- 9 but it may also be introduced at both en s of the screw and discharged in the middle of the screw. The motion of the screw is rapid. The trough of the-screw should not be more than partly filled. v I

Instead of the screw describedany other screw (Fig. 5)

suitable device adapted to agitate and feed the pasty material may be used.

What I claim is: 1.'A- process for converting sugar solutions into crystallized sugar, which comprises evaporating a solution, then lowering the temperature thereof and the relative water content, to cause substantially all of the sugar in the solution to se arate out at a single operation, and then drying and disintegrating the pasty mass resulting from the aforesaid operations; substantially as described. I

2. A process for converting sugar solutions into crystallized sugar,- which consists in converting-a highly heated and concentrated solution into a moistheated paste of crystallized sugar by reducing the relative water content of the solution and lowering the temperature thereof, and then converting such paste into dry fine sugar by agitating the aste and treating it with a current of relatively cold air which eliminates the remainder of the water content; substantially as described.

3. A process for converting sugar solutions into crystallized sugar, WhlCh comprises boiling down a solution to a certain extent, then, without further heating, caussugar, which consists in boiling down the solution at a temperature from 120 to 130 0., reducing the relative water content of such solution and converting the same into a moist hot sugar paste of a temperature of about 70 0., and then subjecting such paste, in a suitable receptacle, to agitation and to the action of a blast of air passed through the same, to complete the elimination of the water content; substantially as described.-

- 5. A process for the direct conversion of sugar solutions into more or less fine, dry sugar, which comprises the bollin down of the solution at a temperature of om 120 eaaeei sugar, which comprises boiling down the solution at a high temperature, corresponding to from 120 to 130 C.', reducing the relative water content of the solution by adding thereto aquantity of loose, drysugar, amounting to at least 50% .of the solutlon, thereby forming a sugar paste of a temperature of about 70 0., and then agitating such paste in a suitable receptacle and passing through the same a blast or current of air to complete the elimination of the water content of the paste; substantially as described.

In testimony whereof signature, in presence of two witnesses.

' CHARLES GRIERE. [1,. s. Witnesses:

OTTO Komc, W. KLEIN.

I have aflixed my 

